NSC 325 Anthropometrics Study Notes

The Nutrition Care Process and Anthropometrics

  • This set of notes covers anthropometrics, weight assessment, malnutrition screening/diagnosis, and related calculations used in nutrition assessment and care planning.

  • Emphasizes how to interpret weight relative to usual weight, ideal body weight (IBW), and body mass index (BMI); how adjustments are made for amputations; and practical considerations when using these metrics in clinical settings.

Nutrition Care Process (NCP) and ADIME

  • NCP is a systematic problem-solving method used by dietetics practitioners to provide safe, effective, high-quality nutrition care.

  • 4 Steps of the NCP (ADIME):

    • A = Assessment

    • D = Diagnosis

    • I = Intervention

    • M&E = Monitoring & Evaluation

  • Content of care includes best evidence, scientific principles, protocols, and process of care.

  • Objective: improve quality of care and health status through a structured, outcome-oriented framework.

Nutrition Screening

  • Purpose: identify individuals that are at nutritional risk or are malnourished; determines if the Nutrition Care Process needs to be completed.

  • It is a requirement of The Joint Commission.

Malnutrition Screening Tool (MST)

  • Step 1: Screen with the MST.

  • Step 2: Score to determine risk:

    • Questions relate to recent weight loss and eating patterns.

    • Weight loss scoring:

    • MST = 0 or 1 → NOT AT RISK

    • MST = 2 or more → AT RISK

    • Weight loss categories:

    • 2–13 lb → score 1

    • 14–23 lb → score 2

    • 24–33 lb → score 3

    • 34 lb or more → score 4

  • If length of stay >7 days, rescreen weekly as needed.

  • Step 3: Intervene with nutritional support for patients at risk of malnutrition; act quickly:

    • If eating poorly due to decreased appetite, appetite score adds to the MST weight loss score for the final MST score.

  • Total MST score ranges from 0–4 (weight loss) plus appetite component; higher scores indicate higher risk.

  • Source attribution: Ferguson et al., Nutrition 1999; Abbott Nutrition toolkit.

The Nutrition Care Process (Detailed)

  • The NCP is a systematic problem-solving method used by dietetics practitioners to critically think and provide safe, effective, high-quality nutrition care.

  • ADIME is the core organization of NCP content:

    • Data collection for Assessment includes:

    • Anthropometric data (A)

    • Biochemical data (B)

    • Health history/current status data (C)

    • Dietary/Physical Activity/Alcohol use, etc. (D)

  • Outcomes of NCP aim to improve health status through evidence-informed care.

Anthropometrics: Data and Interpretation

  • Height: measure whenever possible; height is important for BMI and IBW calculations.

  • Weight: measured with appropriate scales (balance beam, electronic scales, wheelchair/bed scales).

  • Common weight interpretation issues include:

    • Hydration status (over/underhydration)

    • Amputation or limb loss

    • Clothing/shoes, bed/wheelchair limitations

    • Body composition and fat/lean mass distribution

  • Always consider the source and context of weight data; ask where the weight came from and whether it’s accurate.

How to Assess Weight: IBW and Current Weight

  • There is no universal consensus on a single definition of IBW; several formulas exist (Hamwi, Devine, Robinson).

  • What matters clinically is how current weight compares to usual weight and to IBW/IBW range.

  • Key idea: IBW/IBW range provides a reference point, but current-weight adequacy depends on context (e.g., illness, obesity, muscle mass).

Ideal Body Weight (IBW) Calculations

  • Most commonly used: Hamwi equation.

  • Formulas (height in inches, weight in pounds):

    • Male: IBW{M} = 106 + 6 (h{in} - 60)

    • Female: IBW{F} = 100 + 5 (h{in} - 60)

  • Create an Ideal Body Weight range by ±10%:

    • IBWrange=[0.9imesIBW, 1.1imesIBW]IBW_{range} = [0.9 imes IBW,\, 1.1 imes IBW]

  • Examples:

    • Mrs. Smith, 5'2" (62 in): IBW=100+5imes(62−60)=110extlbIBW = 100 + 5 imes (62 - 60) = 110 ext{ lb}

    • IBW range: [0.9imes110,1.1imes110]=[99,121]extlb[0.9 imes 110, 1.1 imes 110] = [99, 121] ext{ lb}

    • %IBW example: if current wt = 166 lb, %IBW = rac{166}{110} imes 100 = 151 ext{%}

  • Use IBW range to assess whether current weight is below, within, or above the IBW range.

Calculating % IBW

  • Procedure: take current weight as the numerator, IBW as the denominator.

  • Formula:

    • ext{
      %IBW} = rac{W}{IBW} imes 100

  • Example: Current weight 150 lb, IBW 110 lb → rac{150}{110} imes 100 \approx 136 ext{%}

Ideal Body Weight Calculations: Worked Examples

  • Female, 5'2"; Current weight = 166 lb; IBW = 110 lb; IBW range = 99–121 lb; %IBW = 151%

  • Male, 6'3"; Current weight = 185 lb; IBW = 196 lb; IBW range = 176–216 lb; %IBW = 94%

  • Another example (from slides):

    • Male, 5'11"; Current weight = 239 lb; IBW = 172 lb; IBW range = 155–189 lb; %IBW = 139%

    • %UBW = 239/254 × 100 = 94% (if usual body weight = 254 lb) using %UBW = current weight / usual weight × 100; weight change = (current - usual) / usual × 100 = -6%

Interpreting Weight for Height

  • Two assessment components:

    • How does current weight compare to Usual Body Weight (UBW)?

    • How does current weight compare to IBW?

  • Current weight vs UBW:

    • Determine percent UBW: ext</p></li></ul></li></ul><p>hoUBW=racWUBWimes100<br>ext{</p></li></ul></li></ul><p>ho UBW} = rac{W}{UBW} imes 100<br>

      • Determine percent weight change: ext</p></li></ul><p>hoChange=racW−UBWUBWimes100<br>ext{</p></li></ul><p>ho Change} = rac{W - UBW}{UBW} imes 100<br>

        • This comparison helps determine whether the person is adequately nourished, malnourished, or at risk for malnutrition.

        • It is considered the most important assessment piece related to weight.

        Malnutrition in Context: Acute Illness or Injury vs Chronic Illness

        • Diagnostic framework (Academy of Nutrition and Dietetics & A.S.P.E.N.): two or more characteristics are needed to diagnose malnutrition state.

        • Clinical characteristics (six possible characteristics):

          • Insufficient energy intake

          • Weight loss

          • Loss of muscle mass

          • Loss of subcutaneous fat

          • Fluid accumulation (edema/ascites)

          • Reduced grip strength

        • Acute illness/injury and chronic illness contexts influence thresholds for energy intake and weight loss:

          • Severe malnutrition often linked to very low energy intake and rapid weight loss; specific percent energy intake and time thresholds vary by context.

          • Moderate malnutrition is a less severe form with less dramatic energy deficits and weight changes.

        • Practical rule: use at least two characteristics to diagnose malnutrition state.

        Interpreting Body Weight: Illustrative Case (Usual Weight and UBW)

        • Example 1 (UBW assessment):

          • 29-year-old male, height 5'10"; current weight 180 lb; usual weight 200 lb (6 months ago).

          • UBW: ext{UBW} = ext{current weight} / ext{usual weight} imes 100 = 180/200 imes 100 = 90 ext{%}

        • Weight change example:

          • Weight change amount: 180 - 200 = -20 lb

          • % Weight change: rac{-20}{200} imes 100 = -10 ext{%}

        • These metrics help determine nutritional risk and needed interventions.

        What Weight to Use for Calculations

        • Core rule: weight is used to calculate energy, protein, and fluid needs.

        • There is debate about using an adjusted weight in certain populations; however, there is no strong evidence to support routine use of Adjusted Body Weight for all patients.

        • General guidelines:

          • If the patient is obese: use actual weight for energy calculations via Mifflin-St Jeor equation; for protein, use IBW or AMDR as appropriate; for fluids, consider 1 mL per kcal or use IBW as applicable.

          • If the patient is not obese: use actual weight for kcal and protein calculations; consider frame size, disease state, and activity level.

        • ICU obesity protocol suggestion (when used): 11–14 kcal/kg actual weight and 2–2.5 g/kg IBW for protein needs.

        Practical Examples: Weight Usage for Calculations

        • Example: Jill, 27-year-old female with IBS; height 5'4"; current weight 125 lb (stable).

          • IBW range: 108–132 lb (depending on frame and height)

          • Use 125 lb (57 kg) for Mifflin Equation (× Activity Factor) and for kcal per kg calculations; use 125 lb (57 kg) for protein and fluid calculations.

        Underweight and Obesity: Weight Use Scenarios

        • Underweight: use ACTUAL weight for calculations when the patient is underweight (e.g., 58-year-old female, weight 110 lb; height 5'7", IBW 135 lb; %IBW = 110/135 × 100 ≈ 81%). For energy, protein, and fluids, use 110 lb (50 kg).

        • Obesity: use actual weight for energy calculations (Mifflin equation with activity factor). For protein: use IBW or AMDR (10–35%). For fluids: use 1 mL per kcal or IBW for guidance.

        • Example: 29-year-old male, height 5'9", current weight 240 lb, IBW ≈ 160 lb; IBW range 144–176 lb.

          • Use 240 lb for energy (Mifflin × AF)

          • Use IBW (160 lb) or AMDR for protein (e.g., 10–35%)

          • Use IBW or 1 mL per kcal to determine fluid needs

        Interpreting Body Weight: Additional Case

        • Example: 29-year-old male, height 5'11"; current weight 239 lb; reports 15 lb weight loss in past month.

          • IBW: 172 lb (106 + 11×6)

          • IBW range: 155–189 lb (172 × 0.9 to 172 × 1.1)

          • %IBW: 239 / 172 × 100 ≈ 139%

          • Current UBW relative to usual weight: Usual weight = 254 lb (239 lb + 15 lb weight loss)

          • %UBW: 239 / 254 × 100 ≈ 94%

          • % weight change: 15 / 254 × 100 ≈ 6% weight loss

        Adjusted Weight for Amputations

        • Amputation adjustment concept: to estimate the body weight that would be present if the missing part were intact, adjust using the proportion contributed by the remaining segments.

        • Percentage contributions (examples):

          • Hand: 0.8%

          • Forearm with hand: 3.1%

          • Entire arm: 6.5%

          • Foot: 1.8%

          • Lower leg (below knee) and foot: 7.1%

          • Entire leg: 18.6%

        • Formula (example with below-the-knee amputation, BKA, 7.1%):

          • Wadj=racW1−aW_{adj} = rac{W}{1 - a} where a = rac{%amputation}{100}.

          • So for W = 155 lb and a = 0.071:

          • Wadj=rac1551−0.071=rac1550.929imes1≈166.8extlbW_{adj} = rac{155}{1 - 0.071} = rac{155}{0.929} imes 1 \approx 166.8 ext{ lb}

        • Uses in BMI: the adjusted weight can be used in BMI calculations when amputations are present (height unchanged).

        • Height example: if height is 5'10" and adjusted weight is 167 lb, BMI calculation would be: $$BMI = rac{W_{adj}( ext{kg})}{H^2( ext{m}^2)}; ext{ e.g., } 75.9 ext{ kg} / (1.80 ext{ m})^2 \